1. Field of the Invention
The present invention relates to an air bag apparatus for a vehicle, and more particularly to an air bag apparatus for a vehicle which reduces an influence of heat applied to the air bag.
2. Description of the Related Art
An air bag apparatus for securing a safety of a passenger at a time of colliding is mounted in a vehicle, for example, to a front passenger""s seat side of an instrument panel. The air bag apparatus is structured such that when the vehicle collides, an air bag pushes and breaks a lid on an upper surface of the instrument panel in a moment of time so as to deploy, thereby preventing an upper body of the passenger from colliding with the instrument panel or a front glass. As a related art, there has been disclosed Japanese Patent Application Laid-Open No. 11-321510.
According to the related art mentioned above, a folded air bag is stored in a case having an open end in an upper portion, and an opening is provided on a bottom surface of the case. A retainer having an opening is mounted from the above to a peripheral edge of the opening. An end portion of the air bag is held between the retainer and the peripheral edge of the opening so as to be fixed thereto. An inflator is mounted facing to an inner side of the air bag, and gas discharged out from the inflator is introduced to an inner portion of the air bag from the opening so as to deploy the air bag upward.
In a case of the related art, because the end portion of the air bag is in a state to be confronted with the opening, in a case where said gas with high temperature and high pressure is discharged from the inflator to the opening, there is a possibility that the end portion of the air bag is influenced with the heat of said discharged gas (deterioration of fibers by the heat). Therefore the end portion of the air bag (especially in a vicinity of a mounting port) needs a special reinforcement by comparison with the other portions so that a manufacture of the air bag requires difficult labors.
The present invention is performed from a view of the problem of the related art and provides an air bag apparatus for a vehicle whose end is hardly influenced by a heat of discharged gas.
According to a first aspect of the present invention, a folded air bag is stored in a case having an open end, and an opening is provided on a surface opposite to the open end of the case. A peripheral edge of an opening is formed as a flange protruding toward an inside of the case, and a retainer having a plurality of rectangular openings is mounted from the inside of the case. An end portion of the air bag is held between the retainer and the peripheral edge of the opening so as to be fixed thereto. An inflator is mounted facing to an inner side of the air bag, and the gas discharged out from the inflator is introduced to an inner portion of the air bag so as to deploy the air bag through the open end. The flange extends higher than the end portion of the air bag.
Since the flange protects the end portion of the air bag from a heat of said discharged gas, it is not necessary to reinforce the end portion of the air bag excessively and it is easy to manufacture the air bag. Further, since the flange has an operation of introducing said discharged gas into the inner portion of the air bag without disturbing a flow current of said gas, it is possible to more securely achieve a smooth expansion of the air bag. Further, since the flange increases a rigidity of the peripheral edge portion of the opening, it is possible to make the case thin, so that it is possible to lighten the air bag apparatus.
According to a second aspect of the present invention, in addition to the structure according to the first aspect mentioned above, the retainer comprises a covering surface fitted to the flange and the end portion of the air bag is curved along the flange and is fixed not only between the retainer and the peripheral edge of the opening but also between the retainer and the flange.
According to the second aspect of the present invention, since an area in which the end portion of the air bag is held is relatively large and the end portion of the air bag is held in a curved state, the end portion of the air bag is hard to be drawn out even when the tension is applied.
According to a third aspect of the present invention, in addition to the structure according to the first aspect mentioned above, a plurality of gas injection holes of the inflator exists near a center of the opening of the case. Since it is possible to make the opening and the retainer smaller, it is possible to make the air bag apparatus compact.
According to a fourth aspect of the present invention, in addition to the structure according to the first aspect mentioned above, a bracket comprising one or more grooves on an inner surface thereof is fixed to the lower surface of the case so that the bracket and the retainer surround the inflator. Said discharged gas is effectively conducted to the air bag.